On Fri 20 Nov 21:44 CST 2020, Suman Anna wrote: > On 11/20/20 9:38 PM, Bjorn Andersson wrote: > > On Fri 20 Nov 21:01 CST 2020, Suman Anna wrote: > > > >> The remoteproc framework provides sysfs interfaces for changing > >> the firmware name and for starting/stopping a remote processor > >> through the sysfs files 'state' and 'firmware'. The 'recovery' > >> sysfs file can also be used similarly to control the error recovery > >> state machine of a remoteproc. These interfaces are currently > >> allowed irrespective of how the remoteprocs were booted (like > >> remoteproc self auto-boot, remoteproc client-driven boot etc). > >> These interfaces can adversely affect a remoteproc and its clients > >> especially when a remoteproc is being controlled by a remoteproc > >> client driver(s). Also, not all remoteproc drivers may want to > >> support the sysfs interfaces by default. > >> > >> Add support to deny the sysfs state/firmware/recovery change by > >> introducing a state flag 'deny_sysfs_ops' that the individual > >> remoteproc drivers can set based on their usage needs. The default > >> behavior is to allow the sysfs operations as before. > >> > > > > This makes sense, but can't we implement attribute_group->is_visible to > > simply hide these entries from userspace instead of leaving them > > "broken"? > > I would have to look into that, but can that be changed dynamically? > Also, note that the enforcement is only on the writes/stores which impact > the state-machine, but not the reads/shows. > > For PRU usecases, we will be setting this dynamically. > It looks to be dynamic, but I don't know if there's any "caching" involved. Please have a look and let me know. Regards, Bjorn > regards > Suman > > > > > Regards, > > Bjorn > > > >> Signed-off-by: Suman Anna <s-anna@xxxxxx> > >> --- > >> v2: revised to account for the 'recovery' sysfs file as well, patch > >> description updated accordingly > >> v1: https://patchwork.kernel.org/project/linux-remoteproc/patch/20180915003725.17549-5-s-anna@xxxxxx/ > >> > >> drivers/remoteproc/remoteproc_sysfs.c | 12 ++++++++++++ > >> include/linux/remoteproc.h | 2 ++ > >> 2 files changed, 14 insertions(+) > >> > >> diff --git a/drivers/remoteproc/remoteproc_sysfs.c b/drivers/remoteproc/remoteproc_sysfs.c > >> index bd2950a246c9..3fd18a71c188 100644 > >> --- a/drivers/remoteproc/remoteproc_sysfs.c > >> +++ b/drivers/remoteproc/remoteproc_sysfs.c > >> @@ -49,6 +49,10 @@ static ssize_t recovery_store(struct device *dev, > >> { > >> struct rproc *rproc = to_rproc(dev); > >> > >> + /* restrict sysfs operations if not allowed by remoteproc drivers */ > >> + if (rproc->deny_sysfs_ops) > >> + return -EPERM; > >> + > >> if (sysfs_streq(buf, "enabled")) { > >> /* change the flag and begin the recovery process if needed */ > >> rproc->recovery_disabled = false; > >> @@ -158,6 +162,10 @@ static ssize_t firmware_store(struct device *dev, > >> char *p; > >> int err, len = count; > >> > >> + /* restrict sysfs operations if not allowed by remoteproc drivers */ > >> + if (rproc->deny_sysfs_ops) > >> + return -EPERM; > >> + > >> err = mutex_lock_interruptible(&rproc->lock); > >> if (err) { > >> dev_err(dev, "can't lock rproc %s: %d\n", rproc->name, err); > >> @@ -225,6 +233,10 @@ static ssize_t state_store(struct device *dev, > >> struct rproc *rproc = to_rproc(dev); > >> int ret = 0; > >> > >> + /* restrict sysfs operations if not allowed by remoteproc drivers */ > >> + if (rproc->deny_sysfs_ops) > >> + return -EPERM; > >> + > >> if (sysfs_streq(buf, "start")) { > >> if (rproc->state == RPROC_RUNNING) > >> return -EBUSY; > >> diff --git a/include/linux/remoteproc.h b/include/linux/remoteproc.h > >> index 3fa3ba6498e8..dbc3767f7d0e 100644 > >> --- a/include/linux/remoteproc.h > >> +++ b/include/linux/remoteproc.h > >> @@ -508,6 +508,7 @@ struct rproc_dump_segment { > >> * @has_iommu: flag to indicate if remote processor is behind an MMU > >> * @auto_boot: flag to indicate if remote processor should be auto-started > >> * @autonomous: true if an external entity has booted the remote processor > >> + * @deny_sysfs_ops: flag to not permit sysfs operations on state, firmware and recovery > >> * @dump_segments: list of segments in the firmware > >> * @nb_vdev: number of vdev currently handled by rproc > >> * @char_dev: character device of the rproc > >> @@ -545,6 +546,7 @@ struct rproc { > >> bool has_iommu; > >> bool auto_boot; > >> bool autonomous; > >> + bool deny_sysfs_ops; > >> struct list_head dump_segments; > >> int nb_vdev; > >> u8 elf_class; > >> -- > >> 2.28.0 > >> >
